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Ann. Geophys., 14, 1506-1512, 1996
www.ann-geophys.net/14/1506/1996/
© European Geosciences Union 1996

Current state-of-the-art for the measurement of non-Maxwellian plasma parameters with the EISCAT UHF Facility

D. Hubert¹, F. Leblanc¹, and P. Gaimard^2
1Departement de Recherche Spatiale, CNRS-URA 264, Observatoire de Paris, 92195 Meudon Cedex, France
²Cephag, Domaine Universitaire, BP 46, 38402 St.-Martin d'Hères, France

Abstract. New results on the information that can be extracted from simulated non-Maxwellian incoherent radar spectra are presented. The cases of a pure ionosphere and of a composite ionosphere typical of a given altitude of the auroral F region are considered. In the case of a pure ionosphere of NO⁺ or O⁺ ions it has been shown that the electron temperature and the electron density can be derived from a Maxwellian analysis of radar spectra measured at aspect angles of 0° or 21° respectively; the ion temperature and ion temperature anisotropy can be derived from a non- constraining model such as the 1D Raman fitting of a complementary measurement made at an aspect angle larger than 0° for the NO⁺ ions, or at an aspect angle larger than 21° for the O⁺ ions. Moreover with such measurements at large aspect angles, the shape of the velocity ion distribution functions can simultaneously be inferred. The case of a composite ionosphere of atomic O⁺ and molecular NO⁺ ions is a difficult challenge which requires simultaneously a complementary measurement of the electron temperature to provide the ion composition and the electron density from the incoherent radar spectra at a specific aspect angle of 21°; hence, a model dependent routine is necessary to derive the ion temperatures and ion temperature anisotropies. In the case where the electron temperature is not given, a routine which depends on ion distribution models is required first: the better the ion distribution models are, the more accurately derived the plasma parameters will be. In both cases of a composite ionosphere, the 1D Raman fitting can be used to keep a check on the validity of the results provided by the ion distribution model dependent routine.

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Citation: Hubert, D., Leblanc, F., and Gaimard, P.: Current state-of-the-art for the measurement of non-Maxwellian plasma parameters with the EISCAT UHF Facility, Ann. Geophys., 14, 1506-1512, 1996.   Bibtex   EndNote   Reference Manager